Production of high cetene number diesel fuel oil



May 11, 1937.

v. VOORHEES PRODUCTION OF HIGH CETENE NUMBER DIESEL FUEL OIL Filed Nov.

Psraff/n Wax Cra ck Paraffin Unsafurafed Liou/d Hydrocarbons,

Wax, efc.

Dewsx Unsal'ural'd Low Boiling poi/77 Liquid Hydrocarbons, elc.

Po/merize wifh Mefsl/ic Hal de paraffm Wax Fraofionall y Disfil/ High Cefene Number Diesel Fuel Oil Hydrocarbons Boiling Oufsioe Diesel Fuel Oil Range INVENTOR Vanderveor l/oorhees ATTORN EY Patented May H, 1937 PRODUCTION OF HIGH CETENE NUMBER DIESEL FUEL OIL Vanderveer Voorhees, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Application November 1, 1935, Serial No. 47,812

4 Claims.

This invention relates to fuels for internal combustion engines and more particularly, an improved fuel for auto ignition engines of the Diesel type wherein the fuel is injected directly into the 5 combustion zone. For the satisfactory operation of engines of this type it has been found. necessary to employ fuels which possess low ignition temperatures in order that the ful will burn rapidly when injected into the combustion zone. This requirement is especially important in Diesel engines of the modern high speed type wherein the time allowed for combustion of the fuel is very short.

The fuels previously employed in Diesel engines have varied widely in their combustion characteristics and a standard of comparison has been established known as the cetene number. The cetene number of a fuel is determined by comparison with a mixture of the hydrocarbons cetene and alpha-methyl naphthalene. The proportion of cetene to alpha-methyl naphthalene is varied until the combustion characteristics of the mixture are identical with those of the fuel being tested when employed in an engine under specified conditions. The cetene number is then expressed as the percentage of cetene in the equivalent mixture. Mostof the commercially available Diesel fuels possess cetene numbers in the range of 30 to 50, those fuels made from naphthenic type crude oils having still lower cetene numbers.

It is an object of this invention to provide a fuel which possesses a high cetene number, preferably above 60, and which will at the same time meet the other requirements for satisfactory Diesel fuel such as, for example, volatility, viscbsity and pour point.

According to the present invention, hydrocarbon waxes are subjected to a pyrolytic treatment whereby they are converted into unsaturated compounds, olefinic cracking products and products of dehydrogenation. The resulting unsaturated drocarbons are subsequently treated with a catalyst to convert them into the desired high cetene number Diesel fuels. As an example of this process, paraffin wax of approximately 126 melting point was subjected to cracking by melting and forcing it through a heated coil at a temperature of about 950 to 1050 F. The re sulting distillate was fractionated to separate it into a wax-containing residue and a wax-free distillate. The distillate was treated with 2% by weight of aluminum chloride at a temperature of 210 F. for a period of eight hours. The alumi- 5 num chloride sludge was separated and the oily KTED STATES PATEN'E OFFEE product was neutralized and washed. Distillation of this product yielded three fractions, a gasoline fraction, a Diesel fuel oil fraction, and

a lubricating oil residue.

The Diesel fuel oil fraction was separated and gave the following inspection:

Pour Point Vis. at F. Vis. at 210-F. Distillation Initial 0 F. 3.52 Centistokes 1.34 Centistokes When used as a fuel in a Diesel engine in comparison with a standard reference fuel, as previously described, the synthetic Diesel fuel showed a cetene number of 66.

, This process is illustrated in the accompanying diagrammatic drawing which shows a paraflin wax l which is cracked to give unsaturated liquid hydrocarbons, paraifin wax, etc. 2. of the cracking reaction is dewaxed to separate at u This product catalyst and yield saturated higher boiling point 3 liquid hydrocarbons 5. Fractional distillation of the polymerized material gives a high cetene number Diesel fuel oil 6 and eliminates hydrocarbons boiling outside the Diesel fuel oil range 1.

Various modifications may be made in my process of producing synthetic Diesel fuel oils.

Thus I may employ other catalysts for treating the thermalized parafiin hydrocarbon. For example, I may employ zinc chloride, boron fluoride,

ferric chloride, etc.

The temperature of polymerization may suitably be varied widely. For example, aluminum chloride may be employed at a temperature of F. and BFs may be used at still lower temperatures.

Aluminum chloride may also be used at temperatures above 210 F.; for example, temperatures as high as 400 F. may

be used.

In carrying out the pyrolysis of the hydrocarbon wax I prefer to employ low pressures, usually atmospheric, although pressures as high as 100 pounds per square inch may be used if desired. I may also employa catalyst to facilitate the thermal decomposition of the wax, in which case lower temperatures may be used. For example, I may treat the wax with aluminum chloride at a temperature of 400600 F., in which case pyrolysis and polymerization will occur simultaneously, making it unnecessary to treat separately the pyrolytic product with additional catalysts.

Various waxes may be used as raw material for my process; for example, I may use mineral waxes such as ozokerite, ceresin andthe Montan waxes. Of the petroleum waxes paraflin wax,

petrolatum wax and intermediate amorphous waxes known as slop wax may be used. Before using the wax it should be largely separated from the oil with which it is associated.

Another modification of my process of making high cetene Diesel fuels from hydrocarbon waxes is to subject the wax to cracking in the manner described and treat the product of cracking by any one of the well-known processes of removing unchanged paraffin wax therefrom. For example the cracking still product may be diluted with liquid propane, hexane or naphtha and dewaxed at a suitable low temperature. The resulting de- Waxed oil, after distillation to remove naphtha and diluent and to provide the desired flash point,

may be used directly as a Diesel fuel or it may be further distilled to meet special-volatility requirements. It may also be treated with aluminum chloride or other catalysts as previously de scribed. The wax removed in the dewaxing operation may be returned to the cracking process. A typical Diesel fuel prepared by my process may have a flash point at 165 F., a pour point of 0 F. and a distillation test showing a 10% point of t 440 F., a 90% point of 620 F. and an end point of 720 F. A pour point below 10 F. is usually desirable.

Although this invention has been described with reference to certain specific embodiments thereof, it should be understood that various other modifications may be employed without departing from the spirit of the invention. For

example, my synthetic Diesel fuel of low ignition temperature may, if desired, be blended with other fuels to provide blends having certain desired properties, such as volatility range flash point, etc. I may also add pour point depressors,

preferably of the resinous type produced by interaction of chlorinated paraflin wax with naphthalene, in which case it is not necessary to completely remove unchanged wax from the product.

The scope of the invention will be determined only by the following claims.

I claim:

1. The process of producing an improved Diesel fuel oil of high cetene, number which comprises subjecting a hydrocarbon wax to cracking conditions whereby the saturated paraffin hydrocarbons of said wax are partially converted into unsaturated hydrocarbons and are partially unconverted, treating the conversion products of the cracking reaction with a metallic halide polymerizing catalyst to convert said unsaturated hydrocarbons into saturated hydrocarbons, fractionally distilling the saturated hydrocarbons thus produced to remove therefrom a fraction having the desired volatility characteristics of fuel oils for high speed Diesel engines, said fraction being exemplified by a product having a 10% distillation point of about 440 F., a distillation point of about 620 F. and an end distillation point of about 720 F., and, at some stage in the foregoing process subsequent to the cracking step, chilling to precipitate unchanged paraifin wax and removing said unchanged paraflin wax, to produce a Diesel fuel having a pour point below about 10 F.

2. The processof claim 1 in which the dewaxing operation is carried out between the cracking step and the polymerizing step.

3. The process of producing an improved Diesel fuel oil of high cetene number which comprises subjecting a hydrocarbon wax to cracking conditions whereby the saturated paraffin hydrocarbons of said wax are partially converted into converted, treating the conversion products of the cracking reaction with a metallic halide polymerizing catalyst to convert said unsaturated hydrocarbons into saturated hydrocarbons, fractionally distilling the saturated hydrocarbons thus produced to remove therefrom a fraction having a 10% distillation point of from about 440 F. to about 480 F. and a 90% distillation point of from about 620 F. to about 710 F., and, atsome stage in the foregoing process subsequent to the cracking step, chilling to precipitate unchanged parafiin wax and removing said unchanged paraflin wax, to produce a Diesel fuel having a pour point below about 10 F.

4. The process of claim 3 in which the dewaxing operation is carried out between the cracking step and the polymerizing step. 

